Traditionally, robot manipulator arms are modeled as rigid links that are moved through use of controllers, actuators, and sensors. This rigid body concept works quite well in predicting robot behavior provided the robot moves slowly. However, high accelerated motion causes considerable residual vibration to occur after the robot manipulator reaches its defined end point. This residual vibration results from inherent compliance of the robot's structural elements. These structural elements tend to be lightly damped so that any residual vibration requires considerable additional settling time before the robot is considered to have completed its task.
Positioning is a fundamental function of robot manipulators. In order to achieve high speed and accurate positioning, it is necessary to control the robot's vibratory response in a cost effective manner. The faster the motion, the larger the vibration energies that must be controlled so that both the robot's response time and residual vibration are minimized at the same time. A number of methods have been attempted in recent years to improve the robot's response times and to control the residual vibration. These methods are computationally intensive; and hence, are not cost effective.
Those concerned with these and other problems recognize the need for an improved robot control scheme.